The HdC stars as recently merged white dwarf binaries
Abstract
The hydrogen-deficient carbon star HD 137613 has been reported by Clayton et al. (2005) to have the extraordinary isotopic ratio ^16O/^18O ~ 0.8. The solar system ratio is ~500 and carbon stars typically have yet larger ratios. The explanation proposed for the ^16O/^18O value observed in HD 137613 is that the HdC stars are recently merged white dwarf binaries. The observed supergiant HdC star is a transient post-merger phase. If so, we have the rare opportunity to see helium-burning shell products in a low gravity stellar environment. To test this model we propose to measure the CNO elemental abundances for HD 137613 as well as the other four hydrogen- deficient carbon stars. Comparison of the measure abundances with models will lead to considerable insight into stellar mergers and nucleosynthesis.
- Publication:
-
NOAO Proposal
- Pub Date:
- February 2006
- Bibcode:
- 2006noao.prop..391H